Robotic apparatus and method for assembling a tire to a rim

ABSTRACT

A tire mounting apparatus for mounting a flexible tire on a rim includes a robot having at least one articulated joint and a wrist. The robot is moveable with at least three degrees of freedom along a selectable one of a plurality of programmable predetermined paths. A central processing unit selectively executes any one of the plurality of paths stored in memory. A bead mounting tool is attachable to the wrist of the robot for movement along the selected one of the plurality of programmable predetermined paths of the robot. The tool is orientatable with at least three degrees of freedom independent of the selected one of the plurality of programmable predetermined paths. A workpiece support positions the rim in a predetermined location with respect to the robot and positions the tire in a predetermined orientation with respect to the rim. A signal is generated and sent to the robot corresponding to a size of the rim and tire combination to be assembled. The central processing unit selects one of the plurality of predetermined paths corresponding to the rim and tire size combination. The robot includes one or more sensors for measuring load on the articulated joint and wrist during a tire mounting cycle. The control program includes a sensor monitoring function for stopping movement of the tool in response to a load greater than a predetermined value. A clamp member prevents rotation of the tire with respect to the rim as the tool works a bead of the tire over the rim

This is a continuation of U.S Pat. No. 6,125,904, Ser. No. 09/088,357,filed Jun. 1, 1998.

FIELD OF THE INVENTION

The present invention relates to a robotic apparatus for assembling atire to a rim in an automated fashion with programmable movement capableof adapting for different size tires and rims on the same productionline.

BACKGROUND OF THE INVENTION

Previous devices and methods have been proposed for mounting vehicletires on rims when automatic means are used to spread the tire bead andforce the tire over the rim to produce the assembling operation. In thestate of the known devices, the rim is mounted on a conveyor, and a tireis supported on the rim in a preliminarily assembled relationship. Therim and tire are then moved to the mounting apparatus. The mountingapparatus spreads the bead of the tire and forces the tire over thewheel rim to locate the tire between the wheel rims so that the tire isthen ready for inflation. In the case of a tube-type tire, an additionalstep is required in order to place and locate the tube within the tirecarcass.

The tubeless tire configuration has been conventional in the art for anextended period of time, however in recent years the diameter of therims, width of the tires and height of the tires have been subject toenormous variation and different combinations in an attempt to design avehicle tire suited to a particular vehicle model having the desiredhandling and performance characteristics sought by the purchasingpublic. In view of the wide variety of vehicle tire and rimconfigurations, it has been difficult to provide an automatic mountingdevice capable of adapting to various rim sizes and wheel sizes indifferent combinations without undue downtime in order to reconfigurethe tire mounting head for the specific size of rim and tire to beassembled. Therefore, it would be desirable to provide a tire mountingapparatus capable of efficient, rapid and economical operation whenfaced with a variety of rim sizes and tire sizes on the same tiremounting production line.

SUMMARY OF THE INVENTION

The present invention provides a tire mounting apparatus and methodwhich is continuous and automatic, efficient, rapid and economical inoperation. The present invention discloses a tire mounting apparatus formounting a flexible tire on a rim. The apparatus includes a robot havingat least one articulated joint and a wrist. The robot is moveable withat least three degrees of freedom along at least one of a plurality ofprogrammable predetermined paths. The predetermined path can includevarying one or more of the three dimensional positions of the path, aswell as one or more of the three orientations of the tool, during asingle cycle or rotation. A central processing unit selectively executesany one of the plurality of programmable predetermined paths stored inmemory. A bead mounting tool is attachable to the wrist of the robot formovement along the selected one of the plurality of programmablepredetermined paths of the robot. The tool can be oriented with at leastthree degrees of freedom independent of the selected one of theplurality of programmable predetermined paths. A workpiece supportpositions the rim in a predetermined location with respect to the robotand positions the tire in a predetermined orientation with respect tothe rim. Means for generating at least one signal to the robot isprovided, where the signal corresponds to a size of the rim and tire.The central processing unit selects one of the plurality of programmablepredetermined paths corresponding to the rim and tire size indicated bythe signal. This configuration permits the central processing unit orrobot to sense the rim and tire size, or to receive other inputcorresponding to the rim and tire size in order to adapt “on-the-fly” tovarious rim and tire sizes being produced on the production line. Thepresent invention also allows the control of the bead mounting tool tobe infinitely variable, such that the elevation, angle and/or pitch ofthe tool can be changed during its path around the outer periphery ofthe rim for a particular rim and tire size configuration, and/or thethree dimensional path of the tool can be changed to accommodate theparticular rim and tire size being mounted. By way of example and notlimitation, the path of the tool can be programmed to be eitherelliptical or circular, or curved in three dimensions (e.g. x-axis,y-axis, and z-axis) as required to effectively mount a particular rimand tire size configuration, while the orientation of the tool can beprogrammed to change during a single cycle from a pitch of 0° withrespect to a vertical axis to a pitch of 45° with respect to thevertical axis, while maintaining the yaw angle at a substantiallyconstant angle with respect to the vertical axis or changing the yawangle with respect to the vertical axis, as the rotational orientationof the tool about the vertical axis changes (e.g. rotating through 360°)to maintain a substantially consistent presentation of the tool facewith respect to the rim.

Preferably, the path of the tool is designed and selected to provide theminimum resistance to mounting a particular rim and tire sizecombination. It is also desirable in the present invention to monitorthe internal load sensing functions built into typical robotic drives orarms and compare the sensed load to a predetermined value. The loadsensors can take the form of current sensors for the motors driving themovement of the various joints, and/or stress and strain gauges mountedat appropriate locations on the robotic arm, or combinations thereof. Inthe preferred configuration, the current used to power the motorsresponsible for moving the joints of the robotic arm are monitored andcompared to predetermined values in order to determine if a load greaterthan the predetermined value is experienced as the bead mounting tool ismoved in the selected programmable path for mounting the rim and tirecombination. It is desirable in the present invention to diagnose ifthere is a processing problem. By way of example and not limitation, aprocessing problem can include an incompatible combination of tire andrim (e.g. tire to big for rim, tire to small for rim, missing rim,missing tire, etc.), or lubrication problems, such as a soapermalfunction. The processing problem is diagnosed by sensing the loadrequired to move the tool along the selected programmed path for theparticular rim and tire size combination. It is also desirable in thepresent invention, to program the least resistance path in order toprovide less stress on the tire as it is mounted on the rim to producethe assembled wheel ready for inflation. Furthermore, it is desirable inthe present invention to provide a closed loop feedback system notavailable in prior known tire mounting systems.

Other objects, advantages and applications of the present invention willbecome apparent to those skilled in the art when the followingdescription of the best mode contemplated for practicing the inventionis read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawingswherein like reference numerals refer to like parts throughout theseveral views, and wherein:

FIG. 1 is a detailed cross-sectional view of a bead mounting toolengaging a side wall of a tire for mounting on a rim according to thepresent invention;

FIG. 2 is a simplified schematic view of a robot for moving the beadmounting tool along selected programmable paths for mounting the tire onthe rim and a schematic representation of control means for controllingthe robot positioned at the tire mounting work station of a wheelassembly line;

FIG. 3 is a, detailed perspective view of the bead mounting tool;

FIG. 4 is a flow diagram illustrating the steps for setting upprogrammable paths and/or orientations and/or load limits for the beadmounting tool as the tool moves along the path for each tire and rimsize combination to be assembled; and

FIG. 5 is a flow diagram illustrating the method of assembling variousrim and tire size combinations being produced on the production line“on-the-fly”.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention discloses a robotic apparatus 10 and method forassembling a tire 12 to a rim 14 to produce an assembled wheel ready forinflation. A tire mounting station 16 is provided where the roboticapparatus 10 is positioned in a predetermined location with respect to atire 12 and rim 14 combination to be assembled. The tire mountingstation 16 can be formed as a “stand-alone” mounter, or in combinationwith a “pick-and-place” apparatus for the tire and rim, or as part of apallet conveyor system designated generally 18 of conventionalconstruction which is driven in intermittent movement. The “stand-alone”mounter can require manual positioning of the rim and tire at the tiremounting station 16. The “pick-and-place” apparatus can be separate fromthe robotic apparatus 10, or can be in the form of an interchangeable“pick-and-place” end effector for the robotic apparatus 10. For purposesof illustration, the pallet conveyor system 18 is of conventional, wellknown construction and carries a plurality of spaced pallets which inturn carry a wheel 20 for assembly of the tire 12 with respect to therim 14 of the wheel 20.

At some point on the pallet conveyor system 18, upstream from the tiremounting station 16 or at the tire mounting station 16 immediately priorto activation of the robotic apparatus 10, a tubeless tire 12 is restedin a predetermined inclined position on the rim 14 of the wheel 20 (e.g.by manual positioning, or by positioning with an automated apparatus,such as with a “pick-and-place” machine, or by positioning with arobotic apparatus having a “pick-and-place” end effector). The inclinedposition of the tire 12 on the rim 14 can be such as that shown in FIGS.1 and 2. The edge of the wheel can be resting against a seat 22. The rim14 of the wheel 20 is held in a non-rotatable predetermined positionwith respect to the robotic apparatus 10. The tire 12 of the wheel 20 isheld in a non-rotatable position by a tire-engaging clamp 24. Theconveyor 18 is driven in step by step movement to advance the pallets toa series of work stations, where the tire mounting station 16 isillustrated in FIGS. 1 and 2, and to stop the pallets at each workstation for a predetermined time period between successive steps ofmovement, which time period is employed to perform a work operation onthe tire 12 and rim 14 of the wheel 20 supported on the pallet.

At some point on the conveyor 18 upstream from the tire mounting station16, the tire 12 and rim 14 are soaped as is conventional. The soaper canbe of well known construction by those skilled in the art. As is alsoconventional and well known in the art, it has been found that adequatesoaping of the beads 26, 28 of the tire and/or seats 30, 32 of the rim14 is required in order to provide sufficient lubrication for movementof the beads 26, 28 over the rim 14 in order to engage the seats 30, 32of the rim 14 without damaging the tire 12. In the mechanical tiremounting systems used in the past, it has been difficult, if notimpossible, to determine if there has been a previous failure of thesoaping mechanism prior to the destruction or damage of one or moretires being engaged by the tire mounting mechanism. Except for expensivevision systems or manual inspection, it has also been difficult todetermine if the correct size combination of tire and rim have beenarranged properly for the mounting procedure.

In the preferred configuration of the present invention, control means34 is provided for receiving input signals and processing informationaccording to a program stored in memory. The control means 34 caninclude a microprocessor or central processing unit for executing theinstructions from programs stored in memory. The control means 34 canreceive input from a suitable device 36 corresponding to the size of atire 12 and rim 14 positioned at the tire mounting station 16 forassembly. Based on the tire/rim size input signal, the control means 34selects an appropriate programmable predetermined path for the beadmounting tool 38 to mount the particular size tire 12 and particularsize rim 14 with respect to one another corresponding to the tire andrim size combination indicated by the input signal. Preferably, thecontrol means 34 of the present invention can be preprogrammed with aplurality of programmable predetermined paths for the bead mounting tool38 corresponding to various sizes of tire and rim combinations. Thisallows the robotic wheel assembly apparatus according to the presentinvention to adapt to the particular tire and rim size combinationpositioned at the tire mounting station “on-the-fly” for increasedproductivity by eliminating downtime to reconfigure the tire mountingapparatus for a new tire and rim size combination.

In addition, the configuration of the present invention permits therobotic apparatus to be controlled according to a programmablepredetermined path selected by the control means 34 matching theparticular tire 12 and rim 14 size combination currently positioned atthe tire mounting station 16, and at the same time selecting aprogrammable predetermined orientation of the bead mounting tool 38 asthe tool travels along the particular selected programmablepredetermined path. This permits customization of both the path and theorientation of the bead mounting tool 38 in order to achieve a mountingcycle for the tire 12 to the rim 14 with a resistance force or load thatis less than a predetermined resistance force or load value for theparticular tire and rim size combination in order to keep the stress onthe tire below the predetermined value. This flexibility in programmingthe path, orientation and maximum resistance load values along the pathof travel of the tool eliminates any damage to the tire during themounting procedure by stopping further movement of the tool 38 along thepredetermined path of travel and orientation if the resistance exceeds aprogrammable predetermined value.

The robotic apparatus 10 preferably includes at least one articulatedjoint 40 and a wrist 42. The robotic apparatus 10 is capable of movementwith at least three degrees of freedom along a selectable one of aplurality of programmable predetermined paths. This type of roboticapparatus is conventional and well know to those skilled in the art. Byway of example and not limitation, a suitable robotic apparatus 10 foruse in the present invention can be obtained from Nachi Robotic Systems,Inc. of Novi, Mich. A bead mounting tool 38 is attachable to the wristof the robot 10 for movement along a selected one of a plurality ofprogrammable predetermined paths of the robot. The tool 38 isorientatable with at least three degrees of freedom independent of theselected one of the plurality of programmable predetermined paths of therobot. By way of example and not limitation, the robot 10 is moveablewith at least three degrees of freedom by rotation of the base about afirst axis 44, a second axis 46, and a third axis 48, as best seen inFIG. 2. The orientation of the tool is controlled by movement of theouter end of the robot 10 by rotation about a fourth axis 50, a fifthaxis 52, and a sixth axis 54. As best seen in FIGS. 2 and 3, the beadmounting tool 38 includes a rim-engaging portion 56. The rim-engagingportion 56 locates the tool 38 with respect to the rim 14, andpreferably is adjustable by set screws 58 to adjust the depth ofpenetration of a tire-side-wall-engaging portion or disc 60 with respectto the rim 14.

The present invention preferably includes one or more sensors 62 formonitoring the load of each articulated joint 40 and/or wrist 42 of therobot 10. The sensor 62 can include one or more current monitors,stress/strain gauges, and/or a combination of the two capable ofgenerating a signal corresponding to the load imposed on the beadmounting tool 38, as the tool engages the tire 12 for mounting the firstand second beads 26, 28 on the rim 14. One or more sensors 62 can send asignal to the control means 34 corresponding to the load imposed on thebead mounting tool 38, as the tool moves along the predetermined pathand orientation selected for the particular tire 12 and rim 14 sizecombination currently positioned at the tire mounting station 16. Thecontrol means 34 compares the measured load from the sensors 62 to apredetermined value at each position or along each portion of theprogrammed path to determine if the load has increased to a valuegreater than a predetermined value. If the measured load exceeds thepredetermined value, the control means 34 immediately stops movement ofthe bead mounting tool 38 in order to prevent damage to the tire 12being mounted on the rim 14 at the tire mounting station 16. By way ofexample and not limitation, it is believed that a load sensorconfiguration according to the present invention can be used in order todetermine whether a failure has occurred of the tire soaper and/or rimsoaper mechanisms upstream of the tire mounting station 16.

Referring now to FIG. 4, a simplified flow diagram is presentedillustrating the setup procedure for the control means 34 of the roboticapparatus 10. For each tire and rim size combination to be assembled, aprogrammable predetermined path is stored in memory corresponding to thedesired predetermined three dimensional path of movement of the robotarm supporting the bead mounting tool used to mount the particular tire12 and rim 14 size combination being programmed. In addition, theorientation of the bead mounting tool 38 is programmed in threedimensions or in three degrees of freedom as previously described. Inparticular, the robotic path can be described with three degrees offreedom corresponding to the movements with respect to the first axis44, the second axis 46, and the third axis 48, while the toolorientation can be described with respect to three degrees of freedomcorresponding to the fourth axis 50, the fifth axis 52, and the sixthaxis 54.

If desired for additional diagnostic capabilities, the present inventionpreferably includes programmable predetermined load limits or valuesalong the particular path for the bead mounting tool 38. These loadlimits can be programmed for the particular three dimensional path andorientation of the bead mounting tool as a single predetermined valuefor all paths, or a specific load limit value that varies along the pathfor each particular tire and rim size combination if desired. Theprogrammed path orientation and load limit for each tire and rim sizecombination to be assembled is stored in an appropriate memory location,which can include any type of memory storage device which isconventional and well known to those skilled in the art. By way ofexample and not limitation, memory can include random access memory,dynamic random access memory, magnetic storage means, optical storagemeans, digital and/or analog storage devices. The programming procedureis repeated during setup as many times as required to define theprogrammable path for each tire and rim size combination to beassembled.

Referring now to FIG. 5, the operation of the preferred configuration ofthe robotic apparatus 10 for mounting a tire 12 to a rim 14 is shown ina simplified schematic flow chart. As best seen in FIG. 2, one or moretire/rim size combination sensor 64 is provided for generating a signalto be sent to the control means 34. The control means 34 receives thetire/rim size combination input signal, and in response to the signalretrieves a programmable predetermined path corresponding to thetire/rim size combination in accordance with the program stored inmemory. The control means 34 then operates the robot 10 to move the beadmounting tool 38 along the selected programmable predetermined path andorientation. While the bead mounting tool 38 is moving along theselected programmable predetermined path and orientation, the controlmeans 34 monitors the load sensors 62. The control means 34 determinesif the load is greater than a programmable predetermined value. If theanswer to that query is no, the program continues and the control means34 determines if the programmable path cycle is complete. If the cycleis not complete, the programs returns to the step to continue monitoringthe load sensor. If the sensed load is greater than a programmablepredetermined value, the control means 34 immediately stops furthermovement of the bead mounting tool 38 by the robot 10 in order toprevent damage to the tire 12 being mounted on the rim 14 at the tiremounting station 16. When the programmable path cycle is complete, thecontrol means 34 moves the robot 10 in order to return the bead mountingtool 38 to a rest position, such as that illustrated in FIG. 2positioned away from the tire mounting station 16, so that the mountedtire and rim can be moved along the conveyor and a new tire and rimcombination can be positioned at the tire mounting station 16 foractuation of another cycle for mounting the tire 12 to the rim 14.

In the preferred programmable cycle of the present invention, the beadmounting tool 38 engages the tire 12 adjacent the tire-engaging clamp 24and follows the programmable path around the rim 14 in order to spreadthe first bead 26 over the rim 14 of the wheel 20. After passing throughapproximately 360° with respect to the rim, the bead mounting tool 38 isin the position as shown in FIG. 1. The second bead 28 is then spread inorder to engage the bead 28 over the rim 14 as the bead mounting tool 38is moved along a second portion of the programmable predetermined path,generally corresponding to a second movement around the entire peripheryof the rim 14 in order to position the bead 28 with respect to the rim14. By way of example and not limitation, the second portion of theprogrammable predetermined path of movement can correspond to a reversemovement of the bead mounting tool 38 from the path taken during thefirst portion of the cycle. The robot 10 can drive the bead mountingtool 38 in the opposite rotational movement from that taken during thefirst portion of the programmable predetermined path of movement used tomount the first bead 26 over the rim 14. After completion of the secondportion of the programmable predetermined path of movement around theperiphery of the rim by the bead mounting tool 38, the tire 12 ismounted with respect to the rim 14 with the beads 26, 28 in theappropriate position with respect to seats 30, 32 for inflating the tireat an inflation station downstream from the tire mounting station 16.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiments but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims, which scope is to be accorded the broadestinterpretation so as to encompass all such modifications and equivalentstructures as is permitted under the law.

What is claimed is:
 1. A tire mounting apparatus for mounting a flexibletire on a rim, the apparatus comprising: a bead mounting tool moveablealong a plurality of predetermined paths; means for generating anelectrical signal corresponding to a size of the rim and tire; means forselectively controlling movement of the tool along one of the pluralityof predetermined paths corresponding to the size of the rim and tire inresponse to the electrical signal; and a clamp member for preventingrotation of the tire with respect to the rim as the bead mounting toolworks a bead of the tire over the rim.
 2. The apparatus of claim 1further comprising: a workpiece support for positioning the rim in apredetermined location with respect to the tool and for positioning thetire in a predetermined orientation with respect to the rim.
 3. A tiremounting apparatus for mounting a flexible tire on a rim, the apparatuscomprising: a bead mounting tool moveable along a plurality ofpredetermined paths; means for generating an electrical signalcorresponding to a size of the rim and tire; means for selectivelycontrolling movement of the tool along one of the plurality ofpredetermined paths corresponding to the size of the rim and tire inresponse to the electrical signal; and the bead mounting tool moveablearound an entire periphery of the rim along a first predetermined pathto seat a first bead of the tire on the rim and moveable around theentire periphery of the rim along a second predetermined path to seat asecond bead of the tire on the rim.
 4. The apparatus of claim 3 furthercomprising: the first predetermined path moving the bead mounting toolin a first rotational direction around the periphery of the rim and thesecond predetermined path moving the bead mounting tool in a secondrotational direction in an opposite rotational direction from the firstpredetermined path.
 5. A method for mounting a flexible tire on a rim,the method comprising the steps of: orientating a bead mounting toolmoveable along a plurality of predetermined paths; generating anelectrical signal corresponding to a size of the rim and tire;selectively controlling movement of the tool along one of the pluralityof programmable predetermined paths corresponding to the rim and tiresize in response to the electrical signal; and preventing rotation ofthe tire with respect to the rim with a tire-engaging clamp, as the beadmounting tool works a bead of the tire over the rim.
 6. The method ofclaim 5 further comprising the step of: positioning the rim in apredetermined location with respect to the tool and positioning the tirein a predetermined orientation with respect to the rim on a workpiecesupport.
 7. A method for mounting a flexible tire on a rim, the methodcomprising the steps of: orientating a bead mounting tool moveable alonga plurality of predetermined paths; generating an electrical signalcorresponding to a size of the rim and tire; selectively controllingmovement of the tool along one of the plurality of programmablepredetermined paths corresponding to the rim and tire size in responseto the electrical signal; moving the bead mounting tool around an entireperiphery of the rim along a first predetermined path to seat a firstbead of the tire on the rim; and moving the bead mounting tool aroundthe entire periphery of the rim along a second predetermined path toseat a second bead of the tire on the rim.
 8. The method of claim 7further comprising the steps of: moving the bead mounting tool in afirst rotational direction around the entire periphery of the rim alongthe first predetermined path; and moving the bead mounting tool in asecond rotational direction along the second predetermined path in anopposite rotational direction from the first predetermined path.
 9. In atire mounting apparatus for mounting a flexible tire on a rim, theimprovement comprising: a bead-mounting tool having a rim engagingportion and a tire engaging portion for forcing the bead of the tireover the rim in response to controlled movement of the tool with respectto the rim and tire, the tool moveable along a plurality ofpredetermined paths corresponding to a size of the rim and tire to bemounted; means for electrically controlling movement of the tool and forelectrically selecting one of the plurality of predetermined paths inresponse to the size of the rim and tire to be mounted; and means forpreventing rotation of the tire with respect to the rim with atire-engaging clamp, as the bead mounting tool works a bead of the tireover the rim.
 10. In a tire mounting apparatus for mounting a flexibletire on a rim, the improvement comprising: a bead-mounting tool having arim engaging portion and a tire engaging portion for forcing the bead ofthe tire over the rim in response to controlled movement of the toolwith respect to the rim and tire, the tool moveable along a plurality ofpredetermined paths corresponding to a size of the rim and tire to bemounted; means for electrically controlling movement of the tool and forelectrically selecting one of the plurality of predetermined paths inresponse to the size of the rim and tire to be mounted; moving means formoving the bead mounting tool around an entire periphery of the rimalong a first predetermined path to seat a first bead of the tire on therim; and the moving means for moving the bead mounting tool around theentire periphery of the rim along a second predetermined path to seat asecond bead of the tire on the rim.
 11. The apparatus of claim 10further comprising: the moving means for moving the bead mounting toolin a first rotational direction around the entire periphery of the rimalong the first predetermined path; and the moving means for moving thebead mounting tool in a second rotational direction along the secondpredetermined path in an opposite rotational direction from the firstpredetermined path.